The present invention relates to a field emission display and in particular to a method of forming a fine electrode pattern of field emitting material on a substrate of such a display.
As shown FIG. 1, a conventional field emission display is comprised of a rear substrate 12, a plurality of parallel cathode electrode lines 16 formed on the rear substrate 12, thin films 20 of electron-emitting material formed on the cathode electrodes 16, a front substrate 14 spaced apart from the rear substrate 12 and a plurality of parallel anode electrode lines 18 formed on the undersurface of the front substrate 14. Further for a color display an RGB phosphor layer 22 is formed on top of the anode electrodes 18. When a predetermined voltage applied between a selected anode electrode 18 and a selected cathode 16 electrical current flows in parallel with the film 20. Then electrons are emitted from the surface of the emitter film 20 and accelerated toward the front substrate 14 and collide with the phosphor layer 22 to cause emission of visible light.
As electron emitting material diamond-like carbon, carbon fiber or carbon nanotube are commonly used. And a transparent ITO is generally used as material for cathode electrodes.
A pattern of emitter may be formed by either photolithography or printing. The first method involves forming a thin film of emitter and wet etching to form a desired pattern. According to the second method a carbon material is made in paste and coated on cathode electrodes by a thick film technique such as printing. However, a fine pattern of emitter may be possible with the first method but it requires costly and complex process. The latter is relatively less costly but it is difficult to produce a fine pattern of less than 100 micron because of distances between pixels in a mesh used in a thick film technique.
It is an objective of the present invention to provide a solution to a problem mentioned above. Namely, a method that enables forming of a fine emitter pattern and yet having improved emission efficiency.